GATE CS 1987 Q1-xix — Runtime Environments

Under static (lexical) scoping, a variable reference is resolved in the block in which the procedure is defined, rather than where it is called.

Let's trace the execution step-by-step:

1. Main Program Execution:
   • The global variables are initialized: $\text{global } x = 7$ and $\text{global } y = 8$.
   • Procedure $Q$ is called.
2. Inside Procedure $Q$:
   • $Q$ declares its own local variables $x$ and $y$.
   • Local $x = 3$ and local $y = 4$.
   • $Q$ calls $P(y)$ with the argument $n = 4$.
3. Inside Procedure $P(n)$:
   • $P$ is defined at the global level, so any non-local variable reference in $P$ resolves to the global scope.
   • The assignment is: $x = (n + 2) / (n - 3)$.
   • With $n = 4$, we get: $\text{global } x = (4 + 2) / (4 - 3) = 6 / 1 = 6$.
4. Returning to $Q$:
   • The statement Write(x) at (1) refers to $Q$'s local variable $x$, which is still $3$. Thus, $3$ is printed.
5. Returning to Main Program:
   • The statement Write(x) at (2) refers to the global variable $x$, which was updated to $6$ by procedure $P$. Thus, $6$ is printed.

Therefore, the values printed are $3, 6$.